Photographic exposure apparatus

ABSTRACT

A portable photographic exposure apparatus for making reproductions of loft drawings, body drafts or the like directly from the drawing table on which the drawing is made. A wheeled cabinet structure has a horizontal supporting surface, the height of which is adjustable to the height of a drawing table, with an exposure unit adapted to be mounted on the supporting surface and containing a light source, a set of electric motor driven wheels, and a source of static electricity. The exposure unit is driven over the drawing table to expose a sheet of film which is laid over the drawing on the drawing table to reproduce the drawing. Static electricity projected by the exposure unit presses the film firmly against the drawing to be reproduced. The electric motor is reversible to return the exposure unit to its supporting cabinet. The apparatus may also be used to expose a negative which is subsequently processed to provide positive reproductions of the loft drawing.

United States Patent 1 Zeunen et al.

[ 1 Mar. 27, 1973 [S4] PHOTOGRAPHIC EXPOSURE I APPARATUS [75] Inventors:Bartheld Zeunen, Clarkston; Rex C.

- Grace, Troy; Alvie R. Dunn, Madison Heights, all of Mich,

[73] Assignee: Capitol Reproductions, lnc., Madison Heights, Mich.

[22] Filed: Sept. 3, 1970 [21] Appl. No.: 69,404

[52] US. Cl ..355/84, 355/99 [51] Int. Cl. ..G03b 27/10 [58] Field ofSearch ..355/78, 79, 84, 85, 99,103, 355/113 [5 6] References I CitedUNITED STATES PATENTS 3,254,586 6/1966 Haus ..355/84 2,5l8,208 8/1950Weiss ....355/84 2,550,640 4/1951' Frantz ....355/84 3,303,763 2/1967Kent et al. ..355/l0 Primary ExaminerSamuel S. Matthews AssistantExaminer Richard A; Wintercorn Attorney-Hauke, Gifford and Patalidis[57] ABSTRACT A portable photographic exposure apparatus for makingreproductions of loft drawings, body drafts or the like directly fromthe drawing table on which the drawing'is made. A wheeled cabinetstructurehas a horizontal supporting surface, the height of which isadjustable to the height of a drawing table, with an exposure unitadapted to be mounted on the supporting surface and containing a lightsource, a set of electric motor driven wheels, and a source of staticelectricity. The exposure unit is driven over the drawing table toexpose a sheet of film which is laid over the drawing on the drawingtable to reproduce the drawing. Static electricity projected by theexposure unit presses the .film firmly against the drawing to bereproduced. The

electric motor is reversible to return the exposure unit to itssupporting cabinet. The apparatus may also be used to expose a negativewhich is subsequently processed to provide positive reproductions of theloft drawing. g

6 Claims, 8 Drawing Figures PATENTEDHARZTIQYS SHEET 10F 3 INVENTORSBARTHEL ZEUNEN REXEC. GgACE BY l R UNN ATTORNEYS PATEHTEDmznms SHEET 2BF 3 FIG.3

INVENTORSZ BARTHEL ZEUNEN REX C. GRACE ALVIE R. DUNN ATTORNEYS 1PHOTOGRAPHIC EXPOSURE APPARATUS BACKGROUND OF THE INVENTION 1.Description of the Prior Art In the reproduction of large metal orsynthetic sheet loft drawings and body drafts it is customary to shipthe completed loft drawings to a special facility for photographicprocessing to-make the necessary reproductions. Drawings of this natureare generallymade on large sheets of suitably coated aluminum, syntheticsheets or the like and the shipping and handling for purposes of makingreproductions is a relatively expensive process, particularly as therisk of damage and the poslarge loft drawings, body drafts and the likefor production of accurate photographic reproductions.

SUMMARY OF THE INVENTION The present invention contemplates. an improvedused to expose large sheets of film which are laid on portable exposureunit which can be used to make posi-' tive reproductions of drawings ofthis type directly from the drawing table on which the drawing is made,thereby eliminating the expensiveshipping and handling of the drawing.The film used with this apparatus may consist of commercially availablematerial such as Mylar or other similardimensionally stable materialhaving a coating light sensitive thereon to provide a reproduction whenexposed over the drawing. Such film lends itself to being pinned to thedrawing by an electrostatic charge which according to the presentinvention is projected from an electrode carried directly by theexposure unit.

DESCRIPTION OF THE DRAWINGS For a more complete understanding of theinvention,-

reference may be had to the accompanying drawings illustrating apreferred embodiment of the invention inwhich like reference charactersrefer to like parts through out the several -views,.and in which:

FIG. 1 is a fragmentary perspective view of a drawing table having aloft drawing thereoncovered by a sheet of film and showing the apparatusof the present invenline 4-4 of FIG. 2;

FIG. 5 is a fragmentary perspective view of a portion of the cabinetstructure of the apparatus of FIGS. 2-4;

FIG. 6 is a bottom plan view of the exposure unit embodied in theapparatus;

FIG. 7 is a cross sectional view taken substantially on line 7-7 of FIG.6; and

FIG. 8 is a fragmentary perspective view of a portion of the exposureunit of FIGS. 6 and 7.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIGS. 1 through 4 illustrate adrawing table 10 in cluding a supporting leg 12 and having a loftdrawing 14 thereon. The table 10 may be of conventional construction andthe loft drawing 14 consists of a large metal or synthetic sheet of thekind conventionally used for making drawings of this type. A sheet offilm 15 to be exposed covers at least the main portion of the drawing14.

The apparatus of the present invention includes a cabinet structureindicated generally at 16 and comprising a lower carriage unit 18 and arectangular cabinet 20. The carriage 18 comprises a rectangularframework 22 having vertical corner posts 24 and casters 26 for movingthe unit 16 into position at one end of a drawing table as shown inFIGS. 1 and 3. The

cabinet includesan upper horizontal supporting platform 28 on whichtheexposure unit 30 is normally carried. The supporting platform 28 mayoverextend the ends. of the cabinet 20 as shownin FIGS. 1 and 4 and thephantom lines of FIG. 2, or may be substantially the length of thecabinet 20 as in the solid lines of FIG. 2, to carry an exposure unit 30of any desired length, depending upon the size of the drawing to bereproduced.

As shown in FIGS. 4 and 5, the framework 22 of the carriage 18 has fourvertically extending racks 32 secured thereto and extending upwardlywithin the side walls 34 of the cabinet unit 20. The corners 35 of thecabinet 20 nest within the vertical corner posts 24 of the carriage 18.A shaft 36 is rotatably journaled in the end walls 34 of the cabinet,and a hand wheel 38 is secured to one end of the shaft 36 exteriorly ofthe cabinet. A worm 40 meshes with a gear 42 secured on a shaft 44supported by brackets 46 on the .inner sides of the walls 34. At theirouter ends the shafts 44 carry pinions 48, each of which meshes with oneof the racks 32 so that upon rotation'of shaft 36 by the hand wheel 38the entire cabinet unit 20 will be raised or lowered so that the heightof the platform 28. may be madelevel with the table 10. i l

The exposure unit 30 shown in detail in FIGS. 68, comprises a generallyrectangular box-like structure having side walls 52 and a top wall 56leavingthe bottom open, and is adapted to contain a series offluorescent tube lights 58 which extend substantially throughout thelength of the unit. An additional tube light 60 is disposed above andextends transversely across the lights 58 at each end of the unit toinsure 'suf-' ficient and substantially uniform lighting for properexposure of the film. A pair of axles 62 are mounted in brackets 64secured to the under side of the top wall 56 and carry the wheels 66 onwhich the exposure unit may be moved from the platform 28 across thedrawing table and returned. As seen in FIGS. 3 and 6, one of the axles62' has a bevel gear 68 secured thereto and meshed with a bevel gear 70having a drive shaft 71 ex: tending upwardly therefrom and journaled inthe top wall 56 so as to be driven from an electric motor 72 mountedthereon. The motor 72 is preferably reversible motor and a suitablespeed reduction may be provided between the motor 72 and the wheels 66to propel the exposure unit 30 at the proper speed for correct exposureof the film or negative. A power cable over which the fan is disposed. Abaffle structure 80 is 7 adapted to direct the cooling air over thelights 58 to prevent their overheating.

At the leading edge of the exposure unit 30 a housing 82 having an openbottom carries an electrostatic discharge electrode 84 electricallyconnected to an electrostatic control unit 86 mounted in the cabinet 20.The electrode 84 has a series of depending discharge pins 88 which, whenthe electrode 84 is energized, will discharge an electrostatic fluxfield along the entire leading edge of the exposure unit in advance ofthe leading wheels 66 to produce an electrostatic charge between thefilm and the drawing 14 so the film will be firmly pressed down andsmoothed against the drawing to be reproduced to insure accurateexposure of the film. In the case of a synthetic material drawing, theelectrostatic charge also serves to flatten the drawing 14 to thesurface of the drawing table 10.

At its forward lower edge the housing 82 carries a wiper pad 90 made offelt or other suitable material. The pad 90 is sufficiently weighted tofirmly engage-the film as the exposure unit travels over the film topress out any air pockets that may exist between the film and theunderlying drawing prior to their exposure to the electrostaticdischarge. The pad 90 may be pivotally mounted along the leading edge ofthe housing 82, as shown in FIG. 8, and a handle 92 on a pivot pin 93 isprovided for lifting the pad 90 at the beginning of an operation so thatit can be placed on top of the edge of the film which is first traversedby the exposure unit 30. Another pad 94 of felt or other suitablematerial extends along the trailing edge of the exposure unit andfunctions to the electrostatic charge after exposure of the film hastaken place to facilitate separation of the film from the drawing.

An electrical conductor 96 in the form of a metal strap may be hookedover one edge of the drawing table 10 to engage the loft drawing 14 asshown in FIGS. 1 and 3. The conductor 96 is connected by a ground wire98 to a piece of metal, such as the handle 100 on the cabinet 20, toground the sheet of metal comprising the loft drawing as well as thedrawing table 10, to direct the electrostatic flux field from theelectrode 84 toward the drawing 14 and the table 10.

By means of the apparatus described it is possible to make positivereproductions of loft drawings directly from a drawing table withoutrequiring any handling of the loft drawings. The apparatus may easily bemoved from one drawing table to the next in a drafting room tosuccessively make reproductions from the drawings on all ofthe drawingtables.

It is possible to make positive reproductions in the manner describedunder normal lighting conditions. However, it may be advisable undersome conditions to block out the film from exposure to the normallighting in a drafting room and this may readily be accomplished bypartially unrolling a roll of opaque cloth (not shown) to cover the film,with the roll carried or'engaged by the leading edge of the exposureunit so that the cloth will be rolled up as the unit traverses the film.Similarly, a roll or length of such opaque cloth (not shown) may beattached to the trailing edge of the exposure unit to progressivelycover the exposed portion of the film. t

The apparatus'has been described in connection with the reproduction ofpositives from suitably coated film which is commercially available. Itwill be apparent that the apparatus could also be used to make negativesrather than positive reproductions, although in making negatives fromthe original loft drawings in the manner described it would be necessaryto carry out such process under controlled lighting conditions.

The electrical controls for the exposure unit 30 may be mounted in anyconvenient place, either on the exposure unit itself or within thecabinet 20. The power cable 102, shown in FIG. 1, may extend from theexposure unit 30 to suitable control units, as indicated at 104 in FIG.3, for the various electrical units of the apparatus. A power line 106shown in FIG. 2 is adapted to be plugged into a conventional source ofelectrical power and supplies current to the apparatus.

What I claim as my inventionvis:

l. Exposure apparatus for making a photographic reproduction of a loftdrawing or the like supportably overlying a horizontal drawing tablesurface, comprising a box-like structure having an open bottom andcontaining a light source, a set of wheels on .said structure on whichsame is movable over a sheet of light sensitive exposure film coveringthe drawing to be reproduced, an electrostatic discharge means extendingalong the leading edge of said exposure unit and constructed to directan electrostatic charge toward said film and drawing to thereby adherethe filmhorizontally and smoothly to the drawing as said exposure unitmoves thereover to expose said film, a motor for driving said wheels topropel said exposure unit over said film, means for electricallygrounding the drawing, and control means for energizing said lightsource, said motor and said electrostatic discharge means. V

2. Apparatus according to claim 1 wherein said electrostatic dischargemeans comprises an electrode extending along the leading edge of saidexposure unit and having a series of spaced, downwardly extendingdischarge pins thereon.

3. Apparatus according to claim 1 including means extending along thetrailing edge of said exposure unit for dissipating-the electrostaticcharge between the drawing and the exposed film.

4. Apparatus for photographically exposing film overlying a loft drawingor the like, comprising a housing having exposure lighting means, meansmoving said housing and said drawing with the overlying film relative toeach other in close juxtaposition for progressive exposure of said film,and said housing carrying an elongated electrostatic discharge meansahead of said lighting means for progressively directing anelectrostatic flux field to said film and drawing to adhere sametogether during exposure and means for progressively dissipatingelectrostatic charge from said film and said housing comprises abox-like structure having an open bottom ofa length to overextend thewidth of said film, said lighting means being carried in said housingand adapted to direct exposure light from the open bottom onto said filmimmediately subsequent to electrostatic adherence thereof to saiddrawing as said housing is moved the'reover. 1

1. Exposure apparatus for making a photographic reproduction of a loftdrawing or the like supportably overlying a horizontal drawing tablesurface, comprising a box-like structure having an open bottom andcontaining a light source, a set of wheels on said structure on whichsame is movable over a sheet of light sensitive exposure film coveringthe drawing to be reproduced, an electrostatic discharge means extendingalong the leading edge of said exposure unit and constructed to directan electrostatic charge toward said film and drawing to thereby adherethe film horizontally and smoothly to the drawing as said exposure unitmoves thereover to expose said film, a motor for driving said wheels topropel said exposure unit over said film, means for electricallygrounding the drawing, and control means for energizing said lightsource, said motor and said electrostatic discharge means.
 2. Apparatusaccording to claim 1 wherein said electrostatic discharge meanscomprises an electrode extending along the leading edge of said exposureunit and having a series of spaced, downwardly extending discharge pinsthereon.
 3. Apparatus according to claim 1 including means extendingalong the trailing edge of said exposure unit for dissipating theelectrostatic charge between the drawing and the exposed film. 4.Apparatus for photographically exposing film overlying a loft drawing orthe like, comprising a housing having exposure lighting means, meansmoving said housing and said drawing with the overlying film relative toeach other in close juxtaposition for progressive exposure of said film,and said housing carrying an elongated electrostatic discharge meansahead of said lighting means for progressively directing anelectrostatic flux field to said film and drawing to adhere sametogether during exposure, and means for progressively dissipatingelectrostatic charge from said film and drawing following exposure tofacilitate separation of said film from said drawing.
 5. The apparatusas defined in claim 4 and in which said drawing and film are supportedflat on a drawing table surface, and said means moving said housingcomprises means driving same over the surface of said table from one endto the other of said drawing.
 6. The apparatus as defined in claim 4 andin which said housing comprises a box-like structure having an openbottom of a length to overextend the width of said film, said lightingmeans being carried in said housing and adapted to direct exposure lightfrom the open bottom onto said film immediately subsequent toelectrostatic adherence thereof to said drawing as said housing is movedthereover.